Inorganic materials for use in a lithium-ion secondary battery

ABSTRACT

A cell for use in an electrochemical cell, such as a lithium-ion secondary battery that includes a positive electrode with an active material that acts as a cathode and a current collector; a negative electrode with an active material that acts as an anode and a current collector; a non-aqueous electrolyte; and a separator placed between the positive and negative electrodes. At least one of the cathode, the anode, the electrolyte, and the separator includes an inorganic additive in the form of one or more zeolites having a Si:Al ratio ranging from 2-50 that absorbs one or more of moisture, free transition metal ions, or hydrogen fluoride that become present in the cell. One or more of the cells may be combined in a housing to form a lithium-ion secondary battery. The inorganic additive may also be incorporated as a coating applied to the internal wall of the housing.

FIELD

This invention generally relates to inorganic materials, e.g., trappingagents or additives for use in an electrochemical cell, such as alithium-ion secondary battery. More specifically, this disclosurerelates to the use of zeolites as inorganic trapping agents or additiveslocated in one or more electrodes (positive or negative), in theseparator, or in the electrolyte of a cell used in a lithium-ionsecondary battery.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

The main difference between a lithium-ion battery and a lithium-ionsecondary battery is that the lithium-ion battery represents a batterythat includes a primary cell and a lithium-ion secondary batteryrepresents a battery that includes secondary cell. The term “primarycell” refers to a battery cell that is not easily or safelyrechargeable, while the term “secondary cell” refers to a battery cellthat may be recharged. As used herein a “cell” refers to the basicelectrochemical unit of a battery that contains the electrodes,separator, and electrolyte. In comparison, a “battery” refers to acollection of cell(s), e.g., one or more cells, and includes a housing,electrical connections, and possibly electronics for control andprotection.

Since lithium-ion (e.g., primary cell) batteries are not rechargeable,their current shelf life is about three years, after that, they areworthless. Even with such a limited lifetime, lithium batteries canoffer more in the way of capacity than lithium-ion secondary batteries.Lithium batteries use lithium metal as the anode of the battery unlikelithium ion batteries that can use a number of other materials to formthe anode.

One key advantage of lithium-ion secondary cell batteries is that theyare rechargeable several times before becoming ineffective. The abilityof a lithium-ion secondary battery to undergo the charge-discharge cyclemultiple times arises from the reversibility of the redox reactions thattake place. Lithium-ion secondary batteries, because of the high energydensity, are widely applied as the energy sources in many portableelectronic devices (e.g., cell phones, laptop computers, etc.), powertools, electric vehicles, and grid energy storage.

In operation, a lithium-ion secondary battery generally comprises one ormore cells, which includes a negative electrode, a non-aqueouselectrolyte, a separator, a positive electrode, and a current collectorfor each of the electrodes. All of these components are sealed in acase, an enclosure, a pouch, a bag, a cylindrical shell, or the like(generally called the battery's “housing”). Separators usually arepolyolefin membranes with micro-meter-size pores, which prevent physicalcontact between positive and negative electrodes, while allowing for thetransport of lithium-ions back and forth between the electrodes. Anon-aqueous electrolyte, which is a solution of lithium salt, is placedbetween each electrode and the separator.

During operation, it is desirable that the Coulombic or currentefficiency and the discharge capacity exhibited by the battery remainsrelatively constant. The Coulombic efficiency describes the chargeefficiency by which electrons are transferred within the battery. Thedischarge capacity represents the amount of charge that may be extractedfrom a battery. Lithium-ion secondary batteries may experience adegradation in capacity and/or efficiency due to prolonged exposure tomoisture (e.g., water), hydrogen fluoride (HF), and dissolvedtransition-metal ions (TM^(n+)). In fact, the lifetime of a lithium-ionsecondary battery can become severely limited once 20% or more of theoriginal reversible capacity is lost or becomes irreversible. Theability to prolong the rechargeable capacity and overall lifetime oflithium-ion secondary batteries can decrease the cost of replacement andreduce the environmental risks for disposal and recycling.

DESCRIPTION OF THE DRAWINGS

In order that the disclosure may be well understood, there will now bedescribed various forms thereof, given by way of example, referencebeing made to the accompanying drawings. The components in each of thedrawings may not necessarily be drawn to scale, but rather emphasis isplaced upon illustrating the principles of the invention.

FIG. 1A is a schematic representation of a lithium-ion secondary cellformed according to the teachings of the present disclosure in which aninorganic additive forms a portion of the positive electrode.

FIG. 1B is a schematic representation of another lithium-ion secondarycell formed according to the teachings of the present disclosure inwhich an inorganic additive forms a portion of the negative electrode.

FIG. 1C is a schematic representation of yet another lithium-ionsecondary cell formed according to the teachings of the presentdisclosure in which an inorganic additive forms a coating on theseparator.

FIG. 1D is a still another schematic representation of a lithium-ionsecondary cell formed according to the teachings of the presentdisclosure in which an inorganic additive is dispersed within theelectrolyte.

FIG. 2A is a schematic representation of a lithium-ion secondary batteryformed according to the teachings of the present disclosure showing thelayering of the secondary cells of FIGS. 1A-1D to form a larger mixedcell.

FIG. 2B is a schematic representation of the lithium-ion secondarybattery of FIG. 2A in which an inorganic additive further forms acoating on the internal wall of the housing.

FIG. 3A is a schematic representation of a lithium-ion secondary batteryformed according to the teachings of the present disclosure showing theincorporation of the secondary cells of FIGS. 1A-1D in series.

FIG. 3B is a schematic representation of the lithium-ion secondarybattery of FIG. 3A in which an inorganic additive further forms acoating on the internal wall of the housing.

FIG. 4 is a scanning electron micrograph (SEM) of the surface of acoated separator prepared according to present disclosure.

FIG. 5 is a graphical representation of the normalized dischargecapacity measured as a function of cycles for a cell having aconventional separator and a cell having a coated separator preparedaccording to the present disclosure.

FIG. 6 is a graphical representation of the coulombic efficiencymeasured as a function of cycles for a cell having a conventionalseparator and a cell having a coated separator prepared according to thepresent disclosure.

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no wayintended to limit the present disclosure or its application or uses. Forexample, the zeolites made and used according to the teachings containedherein is described throughout the present disclosure in conjunctionwith a secondary cell for use in a lithium-ion secondary battery inorder to more fully illustrate the structural elements and the usethereof. The incorporation and use of such inorganic materials asadditives in other applications, including without limitation in otherelectrochemical cells, such as for example a primary cell used in alithium-ion battery, is contemplated to be within the scope of thepresent disclosure. It should be understood that throughout thedescription and drawings, corresponding reference numerals indicate likeor corresponding parts and features.

For the purpose of this disclosure, the terms “about” and“substantially” are used herein with respect to measurable values andranges due to expected variations known to those skilled in the art(e.g., limitations and variability in measurements).

For the purpose of this disclosure, the terms “at least one” and “one ormore of” an element are used interchangeably and may have the samemeaning. These terms, which refer to the inclusion of a single elementor a plurality of the elements, may also be represented by the suffix“(s)” at the end of the element. For example, “at least one metal”, “oneor more metals”, and “metal(s)” may be used interchangeably and areintended to have the same meaning.

The present disclosure generally provides an inorganic material thatcomprises, consists essentially of, or consists of one or more types ofa zeolite having a silicon (Si) to aluminum (Al) ratio ranging fromabout 2 to about 50 that can absorb malicious species, such as moisture(H₂O), free transition-metal ions (TM^(n+)), and/or hydrogen fluoride(HF) that may become present or formed within the housing of alithium-ion secondary battery. The removal of these malicious speciesprolongs the battery's calendar and cycle lifetime when the inorganicmaterial is applied to, at least one of, the electrolyte, separator,positive electrode, and negative electrode. The inorganic material mayalso be applied to the inner wall of the housing of the lithium-ionsecondary battery.

In order to deal with the problems as discussed above, the inorganicmaterial acts as a trapping agent or scavenger for the malicious speciespresent within the housing of the battery. The inorganic materialaccomplishes this objective by effectively absorbing moisture, freetransition-metal ions, and/or hydrogen fluoride (HF) selectively, whilehaving no effect on the performance of the non-aqueous electrolyte,including the lithium-ions and organic transport medium containedtherein. The multifunctional inorganic particles may be introduced intothe lithium-ion secondary battery or each cell therein as at least oneof an additive to the positive electrode, an additive to negativeelectrode, and additive to the non-aqueous electrolyte, and as a coatingmaterial applied to the separator.

Referring to FIGS. 1A to 1D, a secondary lithium-ion cell 1 generallycomprises a positive electrode 10, a negative electrode 20, anon-aqueous electrolyte 30, and a separator 40. The positive electrode10 comprises an active material that acts as a cathode 5 for the cell 1and a current collector 7 that is in contact with the cathode 5, suchthat lithium ions 45 flow from the cathode 5 to the anode 15 when thecell 1 is charging. Similarly, the negative electrode 20 comprises anactive material that acts as an anode 15 for the cell 1 and a currentcollector 17 that is in contact with the anode 15, such that lithiumions 45 flow from the anode 15 to the cathode 5 when the cell 1 isdischarging. The contact between the cathode 5 and the current collector7, as well as the contact between the anode 15 and the current collector17, may be independently selected to be direct or indirect contact;alternatively, the contact between the anode 15 or cathode 5 and thecorresponding current collector 17, 7 is directly made.

The non-aqueous electrolyte 30 is positioned between and in contactwith, i.e., in fluid communication with, both the negative electrode 20and the positive electrode 10. This non-aqueous electrolyte 30 supportsthe reversible flow of lithium ions 45 between the positive electrode 10and the negative electrode 20. The separator 40 is placed between thepositive electrode 10 and negative electrode 20, such that the separator40 separates the anode 15 and a portion of the electrolyte 30 from thecathode 5 and the remaining portion of the electrolyte 30. The separator40 is permeable to the reversible flow of lithium ions 45 there through.

Still referring to FIGS. 1A to 1D, at least one of the cathode 5, theanode 15, the electrolyte 30, and the separator 40 includes an inorganicadditive 50A-50D that absorbs one or more of moisture, free transitionmetal ions, or hydrogen fluoride (HF), as well as other maliciousspecies that become present in the cell. Alternatively, the inorganicadditive 50A-50D selectively absorbs moisture, free transition metalions, and/or hydrogen fluoride (HF). This inorganic additive 50A-50D maybe selected to be one or more types of a zeolite having a silicon (Si)to aluminum (Al) ratio ranging from about 2 and 50; alternatively,between about 2 and 25; alternatively, ranging from about 2 to about 20;alternatively, ranging from about 5 to about 15.

According to one aspect of the present disclosure, the inorganicadditive 50A-50D may be dispersed within at least a portion of thepositive electrode 50A (see FIG. 1A), the negative electrode 50B (seeFIG. 1B), the separator 50C (see FIG. 1C), or the electrolyte 50D (seeFIG. 1D). The inorganic additive 50A-50D may also be in the form of acoating applied onto a portion of a surface of the negative electrode50B, the positive electrode 50A, or the separator 50C.

The inorganic additive of the present disclosure comprises at least oneor a combination selected from different types of zeolites having a CHA,CHI, FAU, LTA or LAU framework. The amount of the inorganic additivepresent in the secondary cell may be up to 10 wt. %; alternatively, upto 5 wt. %; alternatively, between 0.1 wt. % and 5 wt. %, relative tothe overall weight of each component in which the inorganic additive ispresent, namely, the positive electrode, the negative the electrode, orthe electrolyte. The amount of the inorganic additive applied as acoating to the separator of the secondary cell may be up to 100%;alternatively, at least 90%; alternatively, greater than 5% up to 100%.

Zeolites are crystalline or quasi-crystalline aluminosilicates comprisedof repeating TO₄ tetrahedral units with T being most commonly silicon(Si) or aluminum (Al). These repeating units are linked together to forma crystalline framework or structure that includes cavities and/orchannels of molecular dimensions within the crystalline structure. Thus,aluminosilicate zeolites comprise at least oxygen (O), aluminum (Al),and silicon (Si) as atoms incorporated in the framework structurethereof. Since zeolites exhibit a crystalline framework of silica (SiO₂)and alumina (Al₂O₃) interconnected via the sharing of oxygen atoms, theymay be characterized by the ratio of SiO₂:Al₂O₃ (SAR) present in thecrystalline framework.

The inorganic additive of the disclosure exhibits a framework topologyof a chabazite (framework notation=“CHA”), chiavennite (CHI), faujasite(FAU), linde type A (LTA), and laumontite (LAU). The framework notationrepresents a code specified by the International Zeolite Associate (IZA)that defines the framework structure of the zeolite. Thus, for example,a chabazite means a zeolite in which the primary crystalline phase ofthe zeolite is “CHA”.

The crystalline phase or framework structure of a zeolite may becharacterized by X-ray diffraction (XRD) data. However, the XRDmeasurement may be influenced by a variety of factors, such as thegrowth direction of the zeolite; the ratio of constituent elements; thepresence of an adsorbed substance, defect, or the like; and deviation inthe intensity ratio or positioning of each peak in the XRD spectrum.Therefore, a deviation of 10% or less; alternatively, 5% or less;alternatively, 1% or less in the numerical value measured for eachparameter of the framework structure for each zeolite as described inthe definition provided by the IZA is within expected tolerance.

According to one aspect of the present disclosure, the zeolites of thepresent disclosure may include natural zeolites, synthetic zeolites, ora mixture thereof. Alternatively, the zeolites are synthetic zeolitesbecause such zeolites exhibit greater uniformity with respect to SAR,crystallite size, and crystallite morphology, as well has fewer and lessconcentrated impurities (e.g. alkaline earth metals).

The inorganic additive 50A-50D may comprise a plurality of particleshaving or exhibiting a morphology that is plate-like, cubic, spherical,or a combination thereof. Alternatively, the morphology ispredominately, spherical in nature. These particles may exhibit anaverage particle size (D₅₀) that is in the range of about 0.01micrometers (□m) to about 15 micrometers (□m); alternatively about 0.05micrometers (□m) to about 10 micrometers (□m); alternatively, 0.5micrometers (□m) to about 7.5 micrometers (□m); alternatively, 1micrometer (□m) to about 5 micrometers (□m); alternatively, greater thanor equal to 0.5 □m; alternatively, greater than or equal to 1 □m;alternatively, less than 5 □m. Scanning electron microscopy (SEM) orother optical or digital imaging methodology known in the art may beused to determine the shape and/or morphology of the inorganic additive.The average particle size and particle size distributions may bemeasured using any conventional technique, such as sieving, microscopy,Coulter counting, dynamic light scattering, or particle imaginganalysis, to name a few. Alternatively, a laser particle analyzer isused for the determination of average particle size and itscorresponding particle size distribution.

The inorganic additive 50A-50D may also exhibit surface area that is inthe range of about 2 m²/g to about 5000 m²/g; alternatively from about 5m²/g to about 2500 m²/g; alternatively, from about 10 m²/g to about 1000m²/g; alternatively, about 25 m²/g to about 750 m²/g. The pore volume ofthe inorganic additive 50A-50D may be in the range of about 0.05 cc/g toabout 3.0 cc/g; alternatively, 0.1 cc/g to about 2.0 cc/g. Themeasurement of surface area and pore volume for the inorganic additivemay be accomplished using any known technique, including withoutlimitation, microscopy, small angle x-ray scattering, mercuryporosimetry, and Brunauer, Emmett, and Teller (BET) analysis.Alternatively, the surface area and pore volume are determined usingBrunauer, Emmett, and Teller (BET) analysis.

The inorganic additive 50A-50D may include a sodium (Na) concentrationof about 0.01 wt. % to about 2.0 wt. % based on the overall weight ofthe inorganic additive. Alternatively, the Na concentration may rangefrom about 0.1 wt. % to about 1.0 wt. %. The inorganic additive may be alithium-ion exchanged zeolite, such that the concentration of lithiumion is about 0.05 wt. % to about 25 wt. %; alternatively, about 0.1 wt.% to about 20 wt. %; alternatively, about 0.2 wt. % to about 15 wt. %,based on the overall weight of the inorganic additive. When desirable,the inorganic additive may further include one or more doping elementsselecting from Li, Na, Al, Mn, Sm, Y, Cr, Eu, Er, Ga, Zr, and Ti.

The active materials in the positive electrode 10 and the negativeelectrode 20 may be any material known to perform this function in alithium-ion secondary battery. The active material used in the positiveelectrode 10 may include, but not be limited to lithium transition metaloxides or transition metal phosphates. Several examples of activematerials that may be used in the positive electrode 10 include, withoutlimitation, LiCoO₂, LiNi_(1−x−y)CoMn_(y)O₂ (x+y≤⅔), zLi₂MnO₃·(1−z)LiNi_(01-31 x−y)Co_(x)Mn_(y)O₂(x−y≤⅔), LiMn₂O₄, Li Ni_(0.5)Mn_(1.5)O₄,and Li FePO₄. The active materials used in the negative electrode 15 mayinclude, but not be limited to graphite and Li₄Ti₅O₁₂, as well assilicon and lithium metal. Alternatively, the active material for use inthe negative electrode is silicon or lithium metal due to theirone-magnitude higher specific capacities. The current collectors 7, 17in both the positive 10 and negative 20 electrodes may be made of anymetal known in the art for use in an electrode of a lithium battery,such as for example, aluminum for the cathode and copper for the anode.The cathode 5 and anode 15 in the positive 10 and negative 20 electrodesare generally made up of two dissimilar active materials.

The non-aqueous electrolyte 30 is used to support theoxidation/reduction process and provide a medium for lithium ions toflow between the anode 15 and cathode 5. The non-aqueous electrolyte 30may be a solution of a lithium salt in an organic solvent. Severalexamples of lithium salts, include, without limitation, lithiumhexafluorophosphate (LiPF₆), lithium bis(oxalato)-borate (LiBOB), andlithium bis(trifluoro methane sulfonyl)imide (LiTFSi). These lithiumsalts may form a solution with an organic solvent, such as, for example,ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate(DEC), dimethyl carbonate (DMC), propylene carbonate (PC), vinylenecarbonate (VC), and fluoroethylene carbonate (FEC), to name a few. Aspecific example of an electrolyte is a 1 molar solution of LiPF₆ in amixture of ethylene carbonate and diethyl carbonate (EC/DEC=50/50 vol.).

The separator 40 ensures that the anode 15 and cathode 5 do not touchand allows lithium ions to flow there through. The separator 40 may be apolymeric membrane comprising, without limitation, polyolefin basedmaterials with semi-crystalline structure, such as polyethylene,polypropylene, and blends thereof, as well as micro-porous poly(methylmethacrylate)-grafted, siloxane grafted polyethylene, and polyvinylidenefluoride (PVDF) nanofiber webs.

According to another aspect of the present disclosure, one or moresecondary cells may be combined to form a lithium-ion secondary battery.In FIGS. 2A and 2B, an example of such a battery 75A is shown in whichthe four (4) secondary cells of FIGS. 1A-1D are layered to form a largersingle secondary cell that is encapsulated to produce the battery 75. InFIGS. 3A and 3B, another example of a battery 75B is shown, in which thefour (4) secondary cells of FIGS. 1A-1D are stacked or placed in seriesto form a larger capacity battery 75B with each cell being individuallycontained. The lithium-ion secondary battery 75A, 75B also includes ahousing 60 having an internal wall in which the secondary cells 1 areenclosed or encapsulated in order to provide for both physical andenvironmental protection. One skilled in the art will understand thatalthough the battery 75A, 75B shown in FIGS. 2A/2B and 3A/3B incorporatethe four secondary cells of FIGS. 1A-1D that a battery 75A, 75B mayinclude any other number of cells. In addition, the battery 75A, 75B mayinclude one or more cells in which the inorganic additive isincorporated with the positive electrode (50A, FIG. 1A), the negativeelectrode (50B, FIG. 1B), the separator (50C, FIG. 1C), or theelectrolyte (50D, FIG. 1D). In fact, all of the cells may have theinorganic additive incorporated in the same way, e.g., 50A, 50B, 50C, or50D. When desirable, the battery 75A, 75B may also include one or morecells in which the inorganic additive 50A-50D is not incorporated orincluded provided that at least one of the cells in the battery 75A, 75Bincorporates the inorganic additive 50A-50D.

The housing 60 may be constructed of any material known for such use inthe art. Lithium-ion batteries generally are housed in three differentmain form factors or geometries, namely, cylindrical, prismatic, or softpouch. The housing 60 for a cylindrical battery may be made of aluminum,steel, or the like. Prismatic batteries generally comprise a housing 60that is rectangular shaped rather than cylindrical. Soft pouch housings60 may be made in a variety of shapes and sizes. These soft housings maybe comprised of an aluminum foil pouch coated with a plastic on theinside, outside, or both. The soft housing 60 may also be apolymeric-type encasing. The polymer composition used for the housing 60may be any known polymeric materials that are conventionally used inlithium-ion secondary batteries. One specific example, among many,include the use of a laminate pouch that comprises a polyolefin layer onthe inside and a polyamide layer on the outside. A soft housing 60 needsto be designed such that the housing 60 provides mechanical protectionfor the secondary cells 1 in the battery 75.

Referring now to only FIGS. 2B and 3B, the inorganic additive 50E mayalso be included as a coating applied onto at least a portion of asurface of the internal wall of the housing 60. When desirable, theinorganic additive 50E applied to the internal wall of the housing 60may be used along with the inclusion of the inorganic additive 50A-50Din one or more of the secondary cells 1 or used separately withsecondary cells that do not individually include the inorganic additive50A-50D.

A variety of factors can cause degradation in lithium-ion secondarybatteries. One of these factors is the existence of various maliciousspecies in the non-aqueous electrolyte. These malicious species includemoisture (e.g., water or water vapor), hydrogen fluoride (HF), anddissolved transition-metal ions (TM^(n +)).

Moisture in the electrolyte mainly arises as a fabrication residue andfrom the decomposition of the organic electrolyte. Although a dryenvironment is desired, the presence of moisture cannot be thoroughlyexcluded during the production of a battery or battery cell. The organicsolvent in the electrolyte is inclined to decompose to yield CO₂ andH₂O, especially when operated at a high temperature. The water (H₂O) canreact with a lithium salt, such as LiPF₆, resulting in the generation oflithium fluoride (LiF) and hydrogen fluoride (HF). The lithium fluoride(LiF), which is insoluble, can deposit on the surfaces of the activematerials of the anode or cathode forming a solid electrolyte interface(SEI). This solid electrolyte interface (SEI) may reduce or retard thelithium-ions (de)intercalation and inactivate the surface of the activematerial, thereby, leading to a poor rate capability and/or capacityloss.

Hydrogen fluoride (HF), when present, may attack the positive electrode,which contains transition metal and oxygen ions, resulting in theformation of more water and transition metal compounds that arecompositionally different from the active material. When water ispresent and acts as a reactant, the reactions that occur may becomecyclic, resulting in continual damage to the electrolyte and the activematerial. In addition, the transition metal compounds that are formedmay be insoluble and electrochemically inactive. These transition metalcompounds may reside on the surface of the positive electrode, thereby,forming an SEI. On the other hand, any soluble transition metalcompounds may dissolve into the electrolyte resulting in transitionmetal ions (TM^(n+)). These free transition metal ions, such as, forexample, Mn²⁺ and Ni²⁺, can move towards the anode where they may bedeposited as an SEI leading to the introduction of a variety ofdifferent reactions. These reactions, which may consume the activematerials of the electrodes and the lithium-ions present in theelectrolyte, can also lead to capacity loss in the lithium-ion secondarybattery.

The specific examples provided in this disclosure are given toillustrate various embodiments of the invention and should not beconstrued to limit the scope of the disclosure. The embodiments havebeen described in a way which enables a clear and concise specificationto be written, but it is intended and will be appreciated thatembodiments may be variously combined or separated without parting fromthe invention. For example, it will be appreciated that all preferredfeatures described herein are applicable to all aspects of the inventiondescribed herein.

Evaluation Method 1—Transition-Metal Cations Trapping Capability of theInorganic Additive

The performance of the inorganic additive with respect to adsorptioncapabilities for Mn²⁺, Ni²⁺, and Co²⁺, are measured in an organicsolvent, namely a mixture of ethylene carbonate and dimethyl carbonate(EC/DMC=50/50 vol.)

The Mn²⁺, Ni²⁺, and Co²⁺ trapping capabilities of the inorganicadditives in the organic solvent are analyzed by ICP-OES. The organicsolvent is prepared, such that it contains 1000 ppm manganese (II),nickel (II), and cobalt (II) perchlorate, respectively. The inorganicadditive in particle form is added as 1 wt. % of the total mass, withthe mixture being stirred for 1 minute, then allowed to stand still at25° C. for 24 hours prior to measuring the decrease of the concentrationof Mn²⁺, Ni²⁺, and Co²⁺.

Evaluation Method 2—HF Scavenging Capability of the Inorganic Additive

The HF scavenging capability of the inorganic additives in thenon-aqueous electrolyte, namely 1 M LiPF6 in a mixture of ethylenecarbonate and dimethyl carbonate (EC/DMC=50/50 vol.), is analyzed by aFluoride ISE meter. The electrolyte solution is prepared, such that itcontains 100 ppm HF. The inorganic additive in particle form is added as1 wt. % of the total mass, with the mixture being stirred for 1 minute,then allowed to stand still at 25° C. for 24 hours prior to measuringthe decrease of F⁻ in the solution.

Below are the reactions in a Li-ion battery with moisture residue.

LiPF₆+H₂O→HF+LiF↓+H₃PO₄ and

LiMO₂+HF→LiF↓+M²⁺H₂O, wherein M stands for a transition metal.

As a result, in order to reduce HF in the electrolyte, the inorganicadditive consumes the HF and moisture residue at the same time, thereby,breaking the reaction chain.

Evaluation Method 3—Separator

The separators are fabricated using a monolayer polypropylene membrane(Celgard 2500, Celgard LLC, North Carolina). Separators with and withoutthe inclusion of the inorganic additive are constructed for performancecomparison. A slurry containing the inorganic additive is coated ontothe separator in two-side form. The slurry is made of 10-50 wt. %inorganic additive particles dispersed in deionized (D.I.) water. Themass ratio of a polymeric binder to the total solids is 1-10%. Thecoating is 5-15 μm in thickness before drying. The thickness of thecoated separator is 25-45 μm. The coated separators are punched into around disks in a diameter of 19 mm.

Evaluation Method 4—Coin-cell Cycling

Coin cells (2025-type) are made for evaluating the inorganic additivesin a electrochemical situation. A coin cell is made with exteriorcasing, spacer, spring, current collector, positive electrode,separator, negative electrode, and non-aqueous electrolyte.

To fabricate films for use with the positive electrode, a slurry is madeby dispersing the active material (AM), such asLiNi_(1/3)Co_(1/3)Mn_(1/3)O₂ and carbon black (CB) powders in ann-methyl-2-pyrrolidone (NMP) solution of polyvinylidene fluoride (PVDF).The mass ratio of AM:CB:PVDF slurry is 90:5:5. In each case, the slurryis blade coated onto aluminum films. After drying and calendaring, thethickness of each positive electrode film formed is measured to be inthe range of 50-150 μm. The positive electrode films are punched intoround disks in a diameter of 12 mm respectively. The mass loading ofactive material is in the range of 5-15 mg/cm².

Lithium metal foil (0.75 mm in thickness) is cut into a round disk in adiameter of 12 mm as the negative electrode.

2025-type coin cells are made along with the abovementioned positive andnegative electrodes, separator as described in Evaluation Method 3, and1 M LiPF₆ in a mixture of ethylene carbonate and dimethyl carbonate(EC/DMC=50/50 vol.) as the electrolyte as further described herein forbattery performance testing. The cells are cycled between 3 and 4.3 V atthe current loadings of C/2 at 25° C. after two C/5 formation cycles.

Example 1

A FAU-type Y zeolite is used as the inorganic additive, which has beenion-exchanged with Li. The particle size is measured as 0.27, 0.43, 3.76μm for D₁₀, D₅₀, and D₉₀, respectively. The surface area is 640 m²/gwith the pore volume of 0.23 cc/g. The SAR is 3.6, and the inorganicadditive contains 0.35 wt. % of Na₂O and 6.36 wt. % of Li₂O.

In the trapping capability test for transition-metal cations, theinorganic additive reduced the Ni²⁺, Mn²⁺, and Co²⁺ in EC/DMC by 63%,77%, and 84%, respectively. In addition, the inorganic additivescavenges 30% HF in the electrolyte solution.

In order to coat the Y zeolite on to onto Celgard 2500 separator, aslurry is made with Y zeolite powder and PVA solution. The weight ratioof inorganic powder to polymer binder is 12.5:1. The solid loading ofthe slurry is 20%. The slurry is coated in two-side form. The thicknessis 7.5 μm for one coating layer. The SEM image of the coated separatoris shown in FIG. 4.

In the first formation cycle, the cell with the conventional barepolypropylene separator shows a discharge capacity of 149.6 mAh/g with86.1% as coulombic efficiency. In contrast, the cell with the coatedseparator of the present disclosure exhibits 145.8 mAh/g and 81.2% forthe discharge capacity and coulombic efficiency, respectively. Coulombicefficiency of each cell reaches above 99.5% after formation cycles.After 100 cycles of C/5 charge-and-discharge, the cell with the coatedseparator has around 0.5% capacity loss, while the cell with theconventional uncoated separator shows approximately 2% degradation. Thecoulombic efficiency of the cell with the coated separator degradesabout 1%, while the degradation observed for the cell with theconventional bare polypropylene separator is 3%. This degradation ofdischarge capacity and coulombic efficiency is shown in more detail inFIGS. 5 and 6, respectively, as a function of cycles. In FIG. 5, thedischarge capacity is shown as a normalized value.

Within this specification, embodiments have been described in a waywhich enables a clear and concise specification to be written, but it isintended and will be appreciated that embodiments may be variouslycombined or separated without parting from the invention. For example,it will be appreciated that all preferred features described herein areapplicable to all aspects of the invention described herein.

Those skilled-in-the-art, in light of the present disclosure, willappreciate that many changes can be made in the specific embodimentswhich are disclosed herein and still obtain alike or similar resultwithout departing from or exceeding the spirit or scope of thedisclosure. One skilled in the art will further understand that anyproperties reported herein represent properties that are routinelymeasured and can be obtained by multiple different methods. The methodsdescribed herein represent one such method and other methods may beutilized without exceeding the scope of the present disclosure.

The foregoing description of various forms of the invention has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. Numerous modifications or variations are possible in light ofthe above teachings. The forms discussed were chosen and described toprovide the best illustration of the principles of the invention and itspractical application to thereby enable one of ordinary skill in the artto utilize the invention in various forms and with various modificationsas are suited to the particular use contemplated. All such modificationsand variations are within the scope of the invention as determined bythe appended claims when interpreted in accordance with the breadth towhich they are fairly, legally, and equitably entitled.

1. A cell for use in an electrochemical cell, such as a lithium-ionsecondary battery, the cell comprising: a positive electrode, thepositive electrode comprising an active material as a cathode for thecell and a current collector that is in contact with the cathode;wherein lithium ions flow from the cathode to the anode when the cell ischarging; a negative electrode, the negative electrode comprising anactive material as an anode for the cell and a current collector that isin contact with the anode; wherein lithium ions flow from the anode tothe cathode when the cell is discharging; a non-aqueous electrolytepositioned between and in contact with both the negative electrode andthe positive electrode; wherein the non-aqueous electrolyte supports thereversible flow of lithium ions between the positive electrode and thenegative electrode; and a separator placed between the positiveelectrode and negative electrode, such that the separator separates theanode and a portion of the electrolyte from the cathode and theremaining portion of the electrolyte; wherein the separator is permeableto the reversible flow of lithium ions there through; wherein at leastone of the cathode, the anode, the electrolyte, and the separatorincludes an inorganic additive that absorbs one or more of moisture,free transition metal ions, or hydrogen fluoride (HF) that becomepresent in the cell; the inorganic additive being one or more types of azeolite having a silicon (Si) to aluminum (Al) ratio ranging from about2 to about
 50. 2. The cell according to claim 1, wherein the inorganicadditive is dispersed within at least a portion of at least one of thepositive electrode, the negative electrode, the electrolyte, and theseparator or is in the form of a coating applied onto a portion of asurface of the negative electrode, the positive electrode, or theseparator.
 3. The cell according to claim 1, wherein the inorganicadditive exhibits one or more zeolite frameworks of CHA, CHI, FAU, LTAand LAU.
 4. The cell according to claim 1, wherein the inorganicadditive comprises particles having a morphology that is plate-like,cubic, spherical, or a combination thereof.
 5. The cell according toclaim 1, wherein the inorganic additive comprises particles having aparticle size (D₅₀) that is in the range of about 0.05 micrometers (μm)to about 5 micrometers (μm).
 6. The cell according to claim 1, whereinthe inorganic additive exhibits a surface area that is in the range ofabout 10 m²/g to about 1000 m²/g and a pore volume in the range of0.1-2.00 cc/g.
 7. (canceled)
 8. The cell according to claim 1, whereinthe inorganic additive includes a sodium (Na) concentration that is lessthan 1 wt. % based on the overall weight of the inorganic additive. 9.The cell according to claim 1, wherein the inorganic additive is alithium-ion exchanged zeolite, such that the concentration of lithiumion is about 0.1 wt. % to about 20 wt. % based on the overall weight ofthe inorganic additive.
 10. The cell according to claim 1, wherein theinorganic additive includes one or more doping elements selecting fromK, Mg, Cu, Ni, Zn, Fe, Ce, Sm, Y, Cr, Eu, Er, Ga, Zr, and Ti.
 11. Thecell according to claim 1, wherein the positive electrode comprises alithium transition metal oxide or a lithium transition metal phosphate;the negative electrode comprises graphite, a lithium titanium oxide,silicon metal, or lithium metal; the separator is a polymeric membrane;and the non-aqueous electrolyte is a solution of a lithium saltdispersed in an organic solvent.
 12. A lithium-ion secondary batterycomprising: one or more secondary cells; and one or more housings, suchthat an internal wall from one of the one or more housings encapsulatesat least one or more of the secondary cells; wherein each of the one ormore secondary cells comprises: a positive electrode, the positiveelectrode comprising an active material as a cathode for the cell and acurrent collector that is in contact with the cathode; wherein lithiumions flow from the cathode to the anode when the cell is charging; anegative electrode, the negative electrode comprising an active materialas an anode for the cell and a current collector that is in contact withthe anode; wherein lithium ions flow from the anode to the cathode whenthe cell is discharging; a non-aqueous electrolyte positioned betweenand in contact with both the negative electrode and the positiveelectrode; wherein the non-aqueous electrolyte supports the reversibleflow of lithium ions between the positive electrode and the negativeelectrode; and a separator placed between the positive electrode andnegative electrode, such that the separator separates the anode and aportion of the electrolyte from the cathode and the remaining portion ofthe electrolyte; wherein the separator is permeable to the reversibleflow of lithium ions there through; wherein at least one of the cathode,the anode, the electrolyte, the separator, and the internal wall of thehousing includes an inorganic additive that absorbs one or more ofmoisture, free transition metal ions, or hydrogen fluoride (HF) thatbecome present in the cell; the inorganic additive being one or moretypes of a zeolite having a silicon (Si) to aluminum (Al) ratio rangingfrom about 2 to about
 50. 13. The battery according to claim 12, whereinthe inorganic additive is dispersed within least a portion of at leastone of the positive electrode, the negative electrode, the electrolyte,and the separator or is in the form of a coating applied onto a portionof a surface of the negative electrode, the positive electrode, theseparator; or the internal wall of the housing.
 14. The batteryaccording to claim 12, wherein the inorganic additive exhibits one ormore zeolite frameworks of CHA, CHI, FAU, LTA and LAU.
 15. The batteryaccording to claim 12, wherein the inorganic additive comprisesparticles having a morphology that is plate-like, cubic, spherical, or acombination thereof.
 16. The battery according to claim 12, wherein theinorganic additive comprises particles having a particle size (D₅₀) thatis in the range of about 0.05 micrometers (μm) to about 5 micrometers(μm).
 17. The battery according to claim 12, wherein the inorganicadditive exhibits a surface area that is in the range of about 10 m²/gto about 1000 m²/g and a pore volume in the range of 0.1-2.0 cc/g. 18.(canceled)
 19. The battery according to claim 12, wherein the inorganicadditive includes a sodium (Na) concentration that is less than 1 wt. %based on the overall weight of the inorganic additive.
 20. The batteryaccording to claim 12, wherein the inorganic additive is a lithium-ionexchanged zeolite, such that the concentration of lithium ion is about0.1 wt. % to about 20 wt. % based on the overall weight of the inorganicadditive.
 21. The battery according to claim 12, wherein the inorganicadditive includes one or more doping elements selecting from K, Mg, Cu,Ni, Zn, Fe, Ce, Sm, Y, Cr, Eu, Er, Ga, Zr, and Ti.
 22. The batteryaccording to claim 12, wherein the positive electrode comprises alithium transition metal oxide or a lithium transition metal phosphate;the negative electrode comprises graphite, a lithium titanium oxide,silicon metal, or lithium metal; the separator is a polymeric membrane;and the non-aqueous electrolyte is a solution of a lithium saltdispersed in an organic solution.